package lagou.MapTest.ListTest;

import java.util.HashSet;
import java.util.Set;

public class HashSetTest {
    public static void main(String[] args) {
        Set<String> s1 = new HashSet<>();
        s1.add("two");
        s1.add("one");
        System.out.println(s1);
        s1.add("one");
    }

}
